Connect Mini-NDN nodes to an outside network
============================================

Mini-NDN nodes can be connected to an outside network indirectly by running NFD on the local machine:

    (Mini-NDN node) ------ (NFD running on the host machine where Mini-NDN is running) ------- (External Network)

## Add a node in root namespace

For this simple example, we use the default topology:

    c----a----b----d

If we want node "a" to connect to the host machine, we need to add a "root" node which has a link with node "a."

To do so, we need to add the following import statement at the top of `bin/minindn`:

```python
from mininet.node import Node
```

Then the following lines can be added to `bin/minindn` before net.start():

```python
root = Node( 'root', inNamespace=False )
net.addLink(root, 'a')
```

Adding these before net.start() is important as node "root" would then be assigned an IP automatically.
Re-install Mini-NDN by issuing the following command in the mini-ndn folder:

    sudo ./install.sh -i

## Configuration

Run Mini-NDN with the simple topology and issue ifconfig on the local machine to confirm the addition of
the interface. You should be able to locate "root-eth0":

    root-eth0 Link encap:Ethernet  HWaddr 3e:eb:77:d2:6f:1f
              inet addr:1.0.0.9  Bcast:1.0.0.11  Mask:255.255.255.252
              inet6 addr: fe80::3ceb:77ff:fed2:6f1f/64 Scope:Link
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:34 errors:0 dropped:0 overruns:0 frame:0
              TX packets:33 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000
              RX bytes:2667 (2.6 KB)  TX bytes:2797 (2.7 KB)

To make the IP address associated with this interface persistent, add the following line to
/etc/network/interfaces and reboot your machine:

    iface root-eth0 inet manual

## Check connection

After rebooting, run Mini-NDN and issue the following command:

    mini-ndn>net
    a a-eth0:b-eth0 a-eth1:c-eth0 a-eth2:root-eth0

Node "a" is connected to "root-eth0". Now issue "ifconfig a-eth2" on node "a":

    mini-ndn>a ifconfig a-eth2
    a-eth2    Link encap:Ethernet  HWaddr fa:76:d4:86:d3:ba
              inet addr:1.0.0.10  Bcast:1.0.0.11  Mask:255.255.255.252

As learned from the previous step, the IP address of root-eth0 is 1.0.0.9.

    mini-ndn>a ping 1.0.0.9
    PING 1.0.0.9 (1.0.0.9) 56(84) bytes of data.
    64 bytes from 1.0.0.9: icmp_seq=1 ttl=64 time=0.137 ms
    64 bytes from 1.0.0.9: icmp_seq=2 ttl=64 time=0.123 ms

The host machine will also be able to ping node "a":

    VirtualBox:~$ ping 1.0.0.10
    PING 1.0.0.10 (1.0.0.10) 56(84) bytes of data.
    64 bytes from 1.0.0.10: icmp_seq=1 ttl=64 time=0.086 ms

## Run NFD on local machine and register route

Start NFD on the local machine by using:

    sudo nfd

The "nfd-start" script cannot be used, since the script allows only one instance of NFD at a time.
The NFD processes running on the Mini-NDN nodes will prevent the "nfd-start" script from working.

Now, using "nfdc register", we can register a route from node "a" in Mini-NDN to the NFD process on the
host machine and from the host machine to an external machine.

Also, if the local machine has a public IP, Mini-NDN nodes can be reached via external machines.